Canon 550d Versus Nikon D90. Both cost around £550 (body only)?

Which one is the best. Please say why.

Here is a basic comparison for you: http://snapsort.com/...-Nikon_D90

Ignore megapixels-if you want more information google "the megapixel myth"

Pay close attention to image quality

Read the reviews on both at www.dpreview.com and decide which one you think fits you.
Then hold both in your hands, change the settings on them. One will feel right, one won't.
Both are outstanding cameras and you can't go wrong with either.

Here is how their sensor performances compare

http://www.dxomark.com/...nd2)/Canon

Many of my colleagues spouses have D90 cameras and find them exceptional.

The best one for YOU, you will have to determine by comparing specifications and visiting a proper camera shop and holding each in your hands

NOTE: the 550D was replaced by the 600D and the D90 was replaced by the D7000

Go here: http://www.digitalreview.ca/content/Canon-Rebel-T2i-EOS-550D-Compared-to-Nikon-D90.shtml

In the real world where camera handling is more important. The D90 is better by well light years. The D90 has proper ergonomics, which means most of what you need is immediately available at your fingertips. The 550D simply can't do that and you to have to faff and then panic when you need to be quick. The closer comparison to the D90 is the 60D.